Electrode holders for electric smelting furnaces



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INVENTOR.. //lZs Jaan /avl/ g AT Tomavs N. J. HAAVIK Aug. 9, 1960 ELECTRODE HOLDERS FOR ELECTRIC SMELTING FURNACES Filed April 11. 1958 United States Patent() ELECTRODE HOLDERS FOR ELECTRIC SMELTING FURNACES Nils Johan Haavik, Oslo, Norway, assignor to Elektrokemisk A/ S, Oslo, Norway, a corporation of Norway In the manufacture of electrode holders for electrode smelting furnaces, it has been found desirable in many instances to build the electrode holder cylindrical so that it will readily pass through the roof of a closed smelting furnace and to make such electrode holder with a minimum diameter so that the opening in the roof of the furnace may be as small as possible.

In operating holders of this general type it is particularly advantageous to have a plurality of contact clamps, usually 6 or 8 in number, which are arranged radially in a pressure ring surrounding the electrode and which are held pressed against the electrode by springs. By having separate clamps the electrode holder may be adjusted either to carry the entire weight of the electrode or to carry a part of the weight while the balance of the weight is carried by bands or ribbons such as are shown for example in U.S. Patent No. 1,972,849 of September 4, 1934. In either case the electrode may be permitted to'slide through the holder by adjusting the individual spring pressures Aand without the necessity of reducing all of the pressure against the electrode or interrupting the current supply. Use of individual contact clamps is especially of importance with self-baking electrodes of the so-called Soderberg type where the electrode surface may become uneven and where the electrode mass in the upper part of the holder is suiciently soft so that the electrode may be shaped by the holder.

Heretofore spiral springs have usually been employed for holding the clamps, but in order -for the spiral springs to have'proper characteristics they had to have considerable length which meant that the outside pressure ring had to be of large diameter or projections had to be made for each spring casing. This made movement of the electrode holder through the roof of the furnace difficult.

In accordance with the present invention l have found it possible to make electrode holders with a relatively small over-all diameter and with excellent spring char acteristics between the pressure ring and the individual contact clamps by using conical disc springs between the pressure ring and each contact clamp. Also by properly proportioning the thickness of the metal in the springs to the height of the cone it has been found possible to get excellent spring characteristics. For example, the conical height of such a spring may advantageously vary between 0.8 to 1.7 times the thickness of the metal of the spring. The disc springs lie in planes perpendicular to radii at their centers and therefore they can be made of substantial size without materially increasing the overall diameter of the device. Ordinarily the discs will have a diameter greater than the aggregate distance from the surface of the electrode to the outer periphery of the clamping ring.

Single disc springs may be used in each position but 1 have found it advantageous to use these .disc springs in pairs. lf desired, more than two disc springs may be used in each position.

,Advantageously the conical disc springs are so mounted 2,948,765 Patented Aug. 9, 1960 that they may change in shape from the original conical form through the yfiat form to an inverted conical form. When a pair of the disc springs is employed a spacer ring should be inserted between the springs at their point of nearest contact and then the free edges will be permitted to move toward each other under pressure. In my illustrative example I have found it advantageous to put the inner diameters of the cones toward each other and put the spacer rings on the insides of the discs leaving their outer peripheries movable, but the reverse position may also be employed. The spacer rings are preferably so shaped that they keep the disc springs properly aligned and prevent relative radial movement.

This invention can readily be understood by reference to the accompanying drawings in which Fig. 1 is a horizontal sectional view through one unit of a pressure ring and its accompanying clamp with the springs between the pressure ring and clamp relaxed as they would be before applying to an electrode.

Fig. 2 is a view corresponding to Fig. 1 with the springs under full tension as for example when the electrode is being put` into the holder.

Fig. 3 is a vertical section of the part shown in Fig. 2, likewise with the springs under full compression.

Fig. 4 is a vertical section corresponding to Fig. 3 but showing the springs under intermediate tension as they might be during normal operation.

Referring to Fig. l, 10 is one of a series of water cooled pressure clamps adapted to fit around an electrode. Outside of pressure clamps 10 are units 12 of a pressure ring. It is understood that a sufficient number of these units will be interconnected at their ends as by hinges 13 to make a continuous flexible pressure ring and that one clamp member 10 is supplied for each pressure ring unit 12. The pressure ring units 12 are made hollow so they can be water cooled. Between each pair of members 10 and 12 are a pair of conical disc springs 14 with a spacer ring 16 interposed between them at their inner diameters so that the peripheries are held spaced apart. The spacer rings 16 are so shaped as to hold the springs 14 against relative radial movement. When these springs are relaxed the members 10 and 12 will be pushed apart as shown in Fig. l. -It may be noted that when the springs 14 are in their relaxed position, their conical height is slightly less than double the thickness of the metal of the spring.

In the center of each member 12 is an opening which is normally covered by a cover plate 18 but through which Y -a bo-lt may be passed when the cover plate is removed. A corresponding internally threaded socket 20 is provided in the clamp `10.

When it is desired to insert an electrode in the holder, the cover plates 18 are removed and bolts as 22 are inserted through the openings in the members 12 and screwed into the sockets 20. By tightening up on these bolts the clamps 10 are drawn outwardly against the pressure rings 12 as shown in Figs. 2 and 3. In this position the conicity of the discs is reversed and there is ample clearance between the clamps 10 and an electrode 24 so that the electrode may readily be slipped into the holder.

As shown in Fig. 3, suspension members 26 and 28 are connected to the pressure ring units 12 and the clamps 10 respectively. These carry the Weight of the electrode as is customary. The connections for introducing water into the clamps and pressure rings are not shown as these are of standard construction. It is understood that the connections for the clamps 10 ordinarily will be made of copper and will serve to conduct the electric current to the clamps.

In Fig. 4 the device is shown in its operating position. Here the disc springs are under tension which holds them approximately parallel but there is substantial room for them to move from the position shown in Fig. 4 to a position just short of that shown in Fig. 1 while "stil-l maintaining pressure on the clamping member. It will be noted that in Fig. 4 the `bolt 22 is removed and the cover plate 118 is screwed back "in gplace.

It may also be notedthat by using the `disc springs 14, their line of `pressure is extended over a very large `part of the surface of the clamping members `10 instead vof being exerted at a relatively small "central area. `'In some instances this may be of value as tendingto prevent any distortion ofthe clamps '10.

Itis understood that the example `shownis given only by way of illustration 'and maybe modified `in many details without departing from Tthe vspirit of my invention.

What `I claim is:

l. In an electrode holder an external pressure ring forming a substantial cylinder 'about the electrode so that it Vcan conveniently pass 'through the nroof 'of an electric furnace, a plurality lof contact 'clamps within `the ring adapted to be 'pressed against an electrode 'and a disc spring associated with each Iclamp 'located in a plane substantially perpendicular to 'the radius of said pressure ring and 'interposed between 'th'e pressure ring and each contact clamp so that the cylindrical form of the holder is not distorted.

2. A structure as specified in claim 1 which further includes removable means associated with Seach clamp arranged to pass through the pressure ring whereby the disc spring may be compressed to reduce the pressure on 'such clamp.

3. A structure as specified in claim 1 in which the disc spring in unloaded form is conical and in which the conical height of the spring is between 0.8 and 1.7 times the thickness of the metalof the spring.

4. .A structure as specified in claim A1 in which the. verall diameter of "the disc 'spring "is greater "than "the distance from the outside of `the pressure ring to the inside fo'f a Contact clamp.

5. .A structure :as 'specified in Vclaim 1 in "which a plurality of ydisc ,springs are employed foreach clamping unit and spacer rings are placed between adjacent edges of :a pair offdiscs with the Ispa'cer rings being formed of sucient thickness to permit the conicity of the discs to be reversed to l'give an operating `length greater than the free height of the disc.

6. A structure `as specied in claim 5 in which the spacerrings are arranged to support the disc against radial movement.

References 'Ctedinithele o'f this patent UNITED `STATES APATENTS 

